
    //单击弹出登录框
    $('#write').click(function(e){
        e.preventDefault();
        $('.login_box').show(500);
    });
    $('.login_content i').click(function(){
        $('.login_box').hide(500);
    });


    //背景流星雨

    var context;

    var arr = new Array();
    var starCount = 800;

    var rains = new Array();
    var rainCount =20;

    //初始化画布及context
    function init(){
        //获取canvas
        var stars = document.getElementById("stars");
        windowWidth = window.innerWidth; //当前的窗口的高度
        stars.width=windowWidth;
        stars.height=window.innerHeight;
        //获取context
        context = stars.getContext("2d");
    }

    //创建一个星星对象
    var Star = function (){
        this.x = windowWidth * Math.random();//横坐标
        this.y = 5000 * Math.random();//纵坐标
        this.text=".";//文本
        this.color = "white";//颜色

        //产生随机颜色
        this.getColor=function(){

            var _r = Math.random();

            if(_r<0.5){
                this.color = "#333";
            }else{
                this.color = "white";
            }

        }

        //初始化
        this.init=function(){
            this.getColor();
        }
        //绘制
        this.draw=function(){
            context.fillStyle=this.color;
            context.fillText(this.text,this.x,this.y);
        }

    }





    //页面加载的时候
    window.onload = function() {

        init();
        //画星星
        for (var i=0;i<starCount;i++) {
            var star = new Star();
            star.init();
            star.draw();
            arr.push(star);
        }

        //画流星
        for (var i=0;i<rainCount;i++) {
            var rain = new MeteorRain();
            rain.init();
            rain.draw();
            rains.push(rain);
        }

        playStars();//绘制闪动的星星
    //    playRains();//绘制流星

    }

    //星星闪起来
    function playStars(){
        for (var n = 0; n < starCount; n++){
            arr[n].getColor();
            arr[n].draw();
        }

        setTimeout("playStars()",100);
    }


    /*流星雨开始*/

    var MeteorRain = function(){
        this.x = -1;
        this.y = -1;
        this.length = -1;//长度
        this.angle = 30; //倾斜角度
        this.width = -1;//宽度
        this.height = -1;//高度
        this.speed = 1;//速度
        this.offset_x = -1;//横轴移动偏移量
        this.offset_y = -1;//纵轴移动偏移量
        this.alpha = 1; //透明度
        this.color1 = "";//流星的色彩
        this.color2 = "";  //流星的色彩
        /****************初始化函数********************/
        this.init = function () //初始化
        {
            this.getPos();
            this.alpha = 1;//透明度
            this.getRandomColor();
            //最小长度，最大长度
            var x = Math.random() * 80 + 150;
            this.length = Math.ceil(x);
//                  x = Math.random()*10+30;
            this.angle = 30; //流星倾斜角
            x = Math.random()+0.5;
            this.speed = Math.ceil(x); //流星的速度
            var cos = Math.cos(this.angle*3.14/180);
            var sin = Math.sin(this.angle*3.14/180) ;
           // this.width = this.length*cos ;  //流星所占宽度
           // this.height = this.length*sin ;//流星所占高度
            this.offset_x = this.speed*cos ;
            this.offset_y = this.speed*sin;
        }

        /**************获取随机颜色函数*****************/
        this.getRandomColor = function (){
            var a = Math.ceil(255-240* Math.random());
            //中段颜色
            this.color1 = "rgba("+a+","+a+","+a+",1)";
            //结束颜色
            this.color2 = "black";
        };


        /***************重新计算流星坐标的函数******************/
        this.countPos = function ()//
        {
            //往左下移动,x减少，y增加
            this.x = this.x - this.offset_x;
            this.y = this.y + this.offset_y;
        }

        /*****************获取随机坐标的函数*****************/
        this.getPos = function () //
        {
            //横坐标200--1200

            this.x = Math.random() * window.innerWidth; //窗口高度
            //纵坐标小于600
            this.y = Math.random() * window.innerHeight;  //窗口宽度
        }
        /****绘制流星***************************/
        this.draw = function () //绘制一个流星的函数
        {
            context.save();
            context.beginPath();
            context.lineWidth = 1; //宽度
            context.globalAlpha = this.alpha; //设置透明度
            //创建横向渐变颜色,起点坐标至终点坐标
            var line = context.createLinearGradient(this.x, this.y,
                this.x + this.width,
                this.y - this.height);



            //分段设置颜色
            line.addColorStop(0, "white");
            line.addColorStop(0.3, this.color1);
            line.addColorStop(0.6, this.color2);
            context.strokeStyle = line;
            //起点
            context.moveTo(this.x, this.y);
            //终点
            context.lineTo(this.x + this.width, this.y - this.height);
            context.closePath();
            context.stroke();
            context.restore();
        }
        this.move = function(){
            //清空流星像素
            var x = this.x+this.width-this.offset_x;
            var y = this.y-this.height;
            context.clearRect(x-3,y-3,this.offset_x+5,this.offset_y+5);
//                  context.strokeStyle="red";
//                  context.strokeRect(x,y-1,this.offset_x+1,this.offset_y+1);
            //重新计算位置，往左下移动
            this.countPos();
            //透明度增加
            this.alpha -= 0.002;
            //重绘
            this.draw();
        }

    }

//绘制流星
   /* function playRains(){

        for (var n = 0; n < rainCount; n++){
            var rain = rains[n];
            rain.move();//移动
            if(rain.y>window.innerHeight){//超出界限后重来
                context.clearRect(rain.x,rain.y-rain.height,rain.width,rain.height);
                rains[n] = new MeteorRain();
                rains[n].init();
            }
        }
        setTimeout("playRains()",2);
    }
*/

    /*流星雨结束*/





